can anyone explain what is synchronous aynchronous in suitescript?

Synchronous waits for each line to complete. Asynchronous won't block, but will continue to process. Example: For synchronous, if 2 API calls take 30 seconds, then the execution time will take a minute, because the 2nd api call will not happen until the 1st api call returns. However with asynchronous, those 2 api calls will happen at the same time, thus reducing the execution time to 30 seconds.

Thankyou How to make the asynchronous to synchronous?

Here is an example from the help docs the .then is what happens once the https get call completes. The catch is for errors

https.get.promise({
    url: '<https://www.testwebsite.com>',
    headers: headerObj
})
    .then(function(response){
        log.debug({
            title: 'Response',
            details: response
        });
    })
    .catch(function onRejected(reason) {
        log.debug({
            title: 'Invalid Get Request: ',
            details: reason
        });
    })

Ok thank you So much

sure! also, login to netsuite --> Help (top right) --> type in your module like N/https in the search bar

Thank you